http://news.bbc.co.uk/hi/english/sci/tech/newsid_1099000/1099278.stm
The article linked to above describes a most interesting creature:
The sea mouse, or Aphrodita, has spines that normally appear deep red in colour. But when light falls on a spine perpendicular to its axis, stripes of different colours appear - strong blues and greens.
The most remarkable feature about the spines is that, not only do they have a highly specialized internal structure giving rise to this behaviour, but they also handle light "with almost 100% efficiency." This is because the light emitted by the spines to create these stripes of color acts as a defense mechanism - the high efficiency is required, because:
"Below a few hundred metres little light reaches the ocean floor, so for the spines to be effective they must make best use of every scrap of light available," said co-researcher Dr Andrew Parker of the University of Oxford.
Of course, all this raises the question - How'd evolution produce THAT?
It couldn't have developed gradually, because for the spines to be effective, they'd have to have popped into existence fully formed, or at least nearly so, enough to get a pretty high efficiency of light transfer. There is, from what the article says, a very high level of complexity needed in the spines to even get close to having the properties observed, and no survival benefits could be realized until they exist - what benefits could accrue from emitting a dim light in one of the darkest places on earth, other than to attract predators?
This seems to me to be a necessary intermediate form - a being which emitted light, but not a specific form of light (or the wrong specific form of light) - and such a form would be doing the equivalent of saying "eat me" to any predators in the area. Of course, once it had somehow made it past that point, it would have a nice defense mechanism... But wouldn't be easier to just evolve a nice hard carapace, or an ability to swim quickly?
If anyone has an explanation, I'd be quite interested in hearing it.
Responses to date:
- "Because evolution doesn't happen only gradually. It often occurs catastrophically, shockingly, huge rapid changes. When unsuccesful we call them monsters. When they work, they are a new species."
I used "emit" in what I felt to be a wholly appropriate sense - that the spines, after performing some various photonic operations upon incoming (faint) light, emitted a brighter, more colorful reincarnation of the same light. I make no claims that said light emitted is created by the creature in some sort of bioluminescent manner, but meant only that it radiated some form of visible radiation in a manner more intense than it received other, similar forms of visible radiation.
Apparently this was not the clearest use of the word. I apologize - hopefully this postscript will clear things up.
I think
Gorgonzola overestimates my subtlety. I do agree with several of his points - I did make an assumption about the role of the creature's lights (as defense), as well as about a few other things.
As to whether this is a "disingenuous attempt to discredit natural selection", I can't say - Certainly, part of my goal in writing this was to make people think about the likelihood of wholly new structures arising in sea animals, but I was also pretty curious as to how such a structure was said to have arisen.
My curiosity remains, of course. Why not bioluminescence? That's been done in a number of other deep sea creatures. It's certainly easier to evolve - it's a simple chemical reaction in certain cells of the creature's body, whereas this is quite a bit more complex. Why would the creature evolve such a complex solution to a problem where there is a clearly simpler (to arrive at), more reliable method?
And as for my "confusion" of evolution and natural selection, my definitions of them are this:
- Evolution - The naturally occuring, spontaneous creation of new species from older, pre-existing (and generally simpler) ones. Generally not reversible - one species generally doesn't "devolve" back to the species it originated from. Example: Mice evolving from rats, because rats couldn't get to some food supplies, since they were too big. (Just an example - I make no claims to its veracity or accuracy.)
- Natural Selection - The naturally occuring, spontaneous culling of certain genotypes of a given species that are less conducive to survival. Example: Dark moths becoming more common than light moths in summer, because light moths stand out against the darker backgrounds in summer. The situation reverses in winter.
- Species - A group of animals with similar characteristics and genetic makeup, with the possibility of inter-breeding. Example: Dogs. Even though Great Danes and Chihuahuas don't ever breed (that I know of), their genetic material is similar enough that a viable offspring could be produced... Presumably with a Great Dane bitch, due to size issues.